Switch



July 12, 1955 R. M. BLEAKNEY ETAL SWITCH 2 Sheetssheet l H. SN RKM n mA N MMR m IB A MJ R.E.// m

July 12, 1955 R. M. BLEAKNEY ETAL SWITCH 2 Sheets-Sheet 2 Filed July 9, 1942 Fl G. 8

l l. a 4 3 INVENToRs EY R. M. BLEAKN BY W R ATTORNEY @nite SWHCH Robert Max Biealmey and Everly .lohn Workman, Albuquerque, N. Mex., assignors to the United ttates of America as represented by the Secretary of the Navy Application July 9, 1942, Serial No. 45%,344

S Claims. (Cl. luz- 7432) This invention relates generally to electrical shortcircuiting means, and more particularly to an electrical switching mechanism of the type operated by the eentrifugal force produced by rotation of a projectile when fired from a gun.

Certain types of projectiles are provided with electrical detonating devices by virtue of which the explosive charge is set off by electricity supplied by a battery provided within the shell body.

One of the diiculties sometimes encountered in the operation of this type of detonating device is that the charge will be exploded too soon after the shell has started on its way, causing damage to the gun.

It is, therefore, an object of this invention to prevent premature detonating of the explosive charge in a projectile.

lt is also an object of this invention to prevent premature operation of an electrical detonating mechanism contained within a projectile.

It is a further object of this invention that in the event an electrical impulse is transmitted to the squib by a fuze mechanism, this impulse will not operate the squib until some time after the projectile has been fired from its gun.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. l is a plan view of a supporting element which lits within a projectile body, embodying the invention;

Fig. 2 is a view in axial section, taken along line 2-2 of Fig. l;

Fig. 3 is a sectional detail view of the time delay circuit-breaker which forms the principal element of the invention, taken along line 3-3 of Fig. l;

Fig. 4 is a View similar to Fig. 3, except that centrifugal force has begun to operate on the mechanism;

Fig. 5 is an enlarged sectional view of the timedelay mechanism showin g its operation completed by centrifugal force and the electrical circuit open;

Fig. 6 is a schematic wiring diagram of the electrical detonating circuit;

Fig. 7 is similar to Fig. 6 except that the time-delay mechanism is shown in the open-circuit position;

Fig. 8 is a sectional view of a modified form of the time delay circuit-breaker showing its position within its supporting element;

Fig. 9 is a schematic wiring diagram of the modified form ofthe electrical detonating circuit; and

Fig 10 is an enlarged sectional View of the modied form of the time delay mechanism showing its operation completed by centrifugal force and the electrical circuit closed. l

Referring now to the drawings, on which like numerals of reference are employed to designate like parts Vclosing means A,v

ment l1, which is substantially cylindrical in shape. 'ljhe supporting element is provided with threads l2 which enable it to be screwed into a suitable place provided with matching threads within the casing of a projectile (not shown). The disposition of this member is such that the axis of rotation X-X of the supporting element will coincide with that of the projectile. internal threads l are provided, into which the usual booster charge may be inserted. A communicating chamber i4 permits the booster charge to be ,tired by the squib i5. l'he squib receives an electrical tiring impulse, in a manner later to be described, at the appropriate time by means of the wires 16 and i7. As will be noted from Figs. l and 2, the squib 15 is held in place by a closure plug lil provided with a thread which may be screwed into the tapped hole 19 provided in the supporting element il.

An electrical time-delay switch mechanism 19 is placed Within a cylindrical opening 21 provided in the supporting element 1i. This switch mechanism is shown in detail in Figs. 3, 4, and 5. A cyclindrlcally shaped outer insulating member 22 is supported within the opening 2l. Within the insulating member 22 a metal tube 23 is fitted. rl`he outer insulating member may be cut away as at 22a to give accessibility for wiring. Annular shoulders 2li are provided on the interior surface of each end or" the tube 23, and the dises 24 and 25 are tted into the ends of the tube against these shoulders and held Yin place by spinning over the rims or' the tube. The

dise 24 should be composed of an electrically conductive material and has a small centrally located hole provided therein, While its central inner surface may be recessed as at 24a. The disc 25 may be made of any suitable material as its purpose is to seal the end of the tube and to act as a support for one end of the spring 26.

The other end of the spring 26 presses against the bottom of an annular channel cut in one end of a plunger or piston 27 which slides with a loose t within the tube 23. The pressure of the spring tends to maintain the plunger in the position in which it is shown in Fig. 3. The plunger 27 is provided with an axial bore 28 which extends from an annular recess 29 at the outer end to a smaller bore 31 at the inner end. The recess 29 is closed by means of a plug 32.

Fitted within the insulating member 22 and abutting the inner end of the metal tube 23 is a disc 33 of suitable insulating material and another disc 34 of electrically conductive material. These discs are also provided with centrally positioned openings or apertures in axial alignment with the hole provided in disc 24. An electrical connection is made between the discs 2d and 34 by means of the centrally disposed wire 35 which also extends through the small bore 3l of the plunger 27 into the axial bore 23. This wire is initially attached to the disc 34 by means of a drop of solder 36, and to the disc 24 by another drop of solder 37. An enlargement 38 is provided on the end of the wire 35 which lies within the axial bore Z8. This enlargement may be made by knotting the end or" the wire and applying a drop of solder,

or may comprise any other suitable arrangement. The

enlargement, however, should be of a size such that it will move fre ely within the axial bore 2.? but will not pull through the smaller bore 3l.

The electrical circuit is shown diagrammatically in Figs. 6 and 7. A battery 39, or other source of electric current is provided within the body of the projectile. A wire 41 leads from this battery 39 to the squib l5, While a return wire 42 from they squib leads to a circuitthence to the other side of the battery through the wire 43. The circuit-closing means A may comprise any device which operates by means of electrical radiations, sound waves, light rays, radiant heat, or by any other suitable means to result in the sending of an electrical impulse through the squib i5 when the projectile is in proximity to a target, or which may actuate the squib in response to a prearranged signal and, per se, forms no part of this invention. An electrical short-circuit across the squib 15 is initially obtained by means of the leads 44 and 45, which run from the wires 41 and 42, respectively, to the rnetal tube 23 and the conductive disc 34, respectively. Thus the initial electrical circuit, in the event the device A should permit a ow of electricity from the battery 39 would be from one side of the battery through lead 43 to the device A, to lead 42, thence through lead 45 to disc 34, wire 35 to disc 24, metal tube 23, lead 44, thence to the other side of the battery 39 through lead dit. The squib 15, being thus short-circuited, would receive no current and the projectile is rendered safe, regardless of the action of the device A.

The operation of the preferred form of the invention here disclosed, therefore, is to break this short-circuit when the projectile is fired from a gun, and only then. In addition, the operation of the device contemplates a short time-lag before it is broken which will enable the projectile to pass beyond the range of nearby objects before the squib 15 is rendered capable of being exploded by the electrical charge controlled by the device &$A.7

The breaking of the short-circuit is controlled by the operation of the plunger 27. When the projectile is at rest, the spring 26 maintains the plunger in the position shown in Fig. 3, as before stated. However', as soon as the projectile is fired, the riliing of the gun causes it to rotate about the axis X-X. inasmuch as the center of mass of the plunger 27 is to one side of the axis of rotation, it will be forced, by centrifugal force,

against the pressure of spring 2s?, toward the outer end of the tube 23 until it reaches the position shown in Fig. 4. In addition to the pressure of the spring, another retarding influence is produced by light oil or other suitable lluid with which the interior of the tube is filled. The plunger is iitted rather loosely within the tube so so to provide enough clearance to allow the passage ol the oil as shown by the arrows 46.

A special advantage results from the presence of the oil. A momentarily heavy shock in handling a projectile might result in compressions of the spring 26 .Si

so as to permit the plunger 27 to open the circuit, whereas the pressure of the oil in the cylinder acts as a buiier to limit movement of the plunger except when acted upon by a continuing force such as that produced by cen trifugal force when a projectile is rotating at high speed.

The length of the wire 3S is such that when the plunger has reached the position shown in Fig. 4, the enlargement 3S will abut the shoulder formed by the junction between the bores 3?. and 2?.. Further outward movement of the plunger will, therefore, result in the severance of the frangible connection between the wire 35 and the drops of solder 36 and 37 on the discs 34 and 24, respectively. When the plunger has reached the end of its travel, as shown in Fig. 5, the wire has been pulled entirely away from the disc 34 and the short-circuit is broken as shown by the electrical diagram in Fig. 7. lt will be understood that the length of the wire 35 may be adjusted so that the movement of the plunger 27 will pull the wire entirely away from both discs but this is not essential to the breaking of the short-circuit. The short-circuit being broken, the squib l5 may be exploded, although it is obvious that it will not be actuated merely by the breaking of the short-circuit. The electrical tiring impulse must be supplied to the squib from the battery by virtue of some operation of the device A, which will be dependent upon the position of the shell with respect to a target, or upon the operation of some prearanged signal means to which it may respond.

In the modified form of the invention as shown in Figs. 8 through l0, the mechanical operation is substantially the same as that previously described in the preferred form of the invention, the main distinction between the two forms being in the electrical detonating circuit. In the modified form, the circuit extends directly from the battery 39 or other source of electrical current through wire 41 to the squib l5. The other side of the circuit extends from the battery 39 to the fuze A and hence to conductive disc 34 through wire 43. As readily seen in Fig. 9, the circuit is normally broken between conductive disc 34 and a corresponding conductive disc 34a'. Wire 4?, completes the circuit from disc 34a to the squib 15.

In Fig. 8, the time-delay switch mechanism is shown in its normal position, wherein the spring 26 retains the plunger 27 in its right-hand position. The connecting wire 35 with its enlargement 38 extends from the axial bore 28 in the plunger 27 through an aperture in the supporting disc 24, and is held in its position by solder 3'7. When the parts are in this position, the electrical circuit is broken between conductive discs 34 and 34a, and, hence, current cannot be supplied to the squib, thus rendering the projectile safe When the projectile has been tired from a riiled gun, centrifugal force will act upon the plunger 27. The oil contained within the cylinder Z3, aided by the action of the spring 26 will tend to overcome a portion of the centrifugal force, thus permitting the plunger 27 to move slowly to its position as shown in Fig. l0. As the plunger 27 nears the end of its displacement, the abutment B formed on wire 35 will rest against the end of the axial here 23 formed in the plunger 27. Further displacement of the plunger 27 will move the wire 35 (breaking the solder 37) to the left, and through apertures formed in conductive discs 34 and 34a, thereby making contact between the conductive discs. Thus, the circuit is closed from the supply source 39 to the squib l5, except for the iure A, and when the fuze A is actuated as previously described, the squib l5 will be detonated, which, in turn, fires the projectile.

While the invention has been described with reference to certain preferred examples thereof which give satisfactory results, it will be understood by those skilled in the art to which the invention pertains, after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention, and it is intended, therefore, to cover in the appended claims all such changes and modifications.

What is claimed is:

l. ln a projectile provided with a squib capable of being exploded electrically, a source of electrical energy within said projectile, ring means for supplying electric current from said source to said squib at the moment it is desired to explode said projectile, an electrical circuit initially short-circuiting said squib, said circuit having a frangible portion, and a relatively heavy mass mechanically connected to said frangible portion, said mass being disposed initially to be free to move radially outward, whereby it is capable of being displaced by centrifugal force to break said frangible portion and thus open said short-circuit.

2. In a projectile, a squib for tiring the same, means 'For detonating the squib including a source of electrical current, a circuit for conducting the current from said source to said squib, and means in said circuit constituting at least one barrier to the flow of current from the source to the squib, said barrier means including a frangible portion which must be fractured to eliminate the barrier, and means mechanically connected to said barrier means and actuated by centrifugal force when the projectile is in Hight, to fracture said frangible portion.

3. in a projectile, a squib for firing the same, means for detonating the squib including a source of electrical T3 current, a circuit for conducting the current from said source to said squib, means to control said circuit, constituting at least one barrier to the ow of current from the source to the squib, said barrier means including a wire and at least one frangible connection therefor in said circuit, and means responsive to the centrifugal` action of the projectile when in ight to act on the wire and fracture the connection to aiect the circuit.

4. ln a projectile, a squic for tiring the same, means for detonating the squib including a source of electrical current, a circuit for conducting the current from said source to said squib, means to control said circuit constituting at least one short-circuiting barrier across sai circuit to divert the current flow from the squih, said barrier including a wire and at least one frangible connection therefor in said circuit, and means responsive to the centrifugal action of the projectile when in flight to act on the wire and fracture the connection to open the short circuit,

5. In a projectile, a squib for tiring the same, means for detonatinU the squib including a source of electrical current. a circuit for conducting the current from said source to said squib, means to control said circuit constituting at least one circuit-opening barrier serially located in said circuit to prevent the current flow to the squib, said barrier including a Wire and at least one frangible connection therefor in said circuit, and means responsive to the centrifugal action of the projectile when in flight to act on the Wire and fracture the connection to close the circuit.

References Cited in the tile of this patent UNITED STATES PATENTS 

